# 获取用户输入的棋盘大小
n = int(input("请输入棋盘大小n(n>2)："))

# 外层循环控制行
for i in range(1, n+1):
    # 内层循环控制列
    for j in range(1, n+1):
        # 判断当前位置应该输出的字符
        if i == 1 and j == 1:
            print("┌", end="")  # 左上角
        elif i == 1 and j == n:
            print("┐", end="")  # 右上角
        elif i == n and j == 1:
            print("└", end="")  # 左下角
        elif i == n and j == n:
            print("┘", end="")  # 右下角
        elif j == 1:
            print("├", end="")  # 左侧一列
        elif j == n:
            print("┤", end="")  # 右侧一列
        elif i == 1:
            print("┬", end="")  # 顶部一行
        elif i == n:
            print("┴", end="")  # 底部一行
        else:
            print("┼", end="")  # 内部
    # 一行结束后换行
    print()